Time division duplex (TDD) is one of full-duplex communications technologies used in a mobile telecommunication system. In a TDD mode, uplink data and downlink data are transmitted in different timeslots on a same carrier. That is, the uplink data and the downlink data are transmitted at different times.
A frame structure of the TDD mode includes an uplink subframe and a downlink subframe. The uplink subframe is used to transmit the uplink data, and the downlink subframe is used to transmit the downlink data. FIG. 1 is a schematic diagram of uplink data transmission in an existing network. In the figure, UL represents an uplink subframe, and DL represents a downlink subframe. As shown in FIG. 1, when a subframe at a time point at which uplink data arrives is a downlink subframe (DL), the uplink data cannot be transmitted, and can be sent only when a next uplink subframe (UL) arrives.
In applications of an existing network, a data volume of a downlink service is usually greater than a data volume of an uplink service. Therefore, there is a relatively small quantity of uplink subframes. For some low-latency services, a wait time for uplink data transmission is quite long, greatly affecting quality of service (QoS) satisfaction of the low-latency services.